1. FIELD OF THE INVENTION
The present invention relates to an electrophotographic copying machine, and more particularly, to an electrophotographic copying machine, wherein copying operation is prohibited when consumption of either one of consumptive parts or materials which are used or consumed upon every copying operation reaches a predetermined value.
2. DESCRIPTION OF RELATED ART
A conventional electrophotographic copying machine comprises articles consumed upon every copying operation such as a cleaning web for removing waste toner adhering to a fixing roller, and a waste such as the waste toner is produced upon every copying operation. When the articles become empty or when a waste container for accommodating the waste becomes full of the waste, it is warned to the operator.
In this type of conventional copying machine, for example, there is provided a waste toner container for accommodating the waste toner produced upon every copying operation. When the weight of the waste toner container becomes larger than a predetermined value, a detecting switch is turned on, and it is displayed that the quantity of the waste toner reaches a predetermined value. Further, the copying operation is automatically suspended as soon as the quantity of the waste toner reaches a predetermined value even though it is during the copying operation.
In another conventional copying machine, there is provided a waste toner full counter for counting the number of copies obtained from an empty state of the waste toner container to a full state thereof. It is judged based on the counting value of the waste toner full counter whether or not the waste toner is to be discarded, and the copying operation is prohibited if it is judged that the waste toner is to be discarded.
In the above copying machine for detecting the timing when the waste toner should be discarded and thereby the copying operation should be prohibited, as soon as the waste toner container becomes full of the waste toner, the copying operation is suspended during the copying operation. Particularly, in the case of the copying operation for obtaining a lot of copies, the operator sets documents on a document tray of an automatic document feeder (referred to as an ADF hereinafter), and presses a start key in order to start the copying operation. Thereafter, the operator leaves the copying machine in order to do other works and returns thereto to take the copied papers and the documents around a timing when the copying operation may have been completed.
In this case, the following state may occur. Namely, after it is displayed that the waste toner container becomes full of the waste toner during the copying operation for obtaining a predetermined number of copies, for example, one thousand copies, the copying operation is suspended automatically. Thereafter, the number of copies obtained actually becomes less than the predetermined one although the copying machine has been stopped as if the copying operation has been completed. At that time, the operator opens the front door of the copying machine, draws out the waste toner container, and discards the waste toner from the waste toner container. Then, the operator sets the waste toner container at a predetermined position of the copying machine, and presses the start key so as to start the copying operation for remaining copies.
As described above, if the waste toner container becomes full of the waste toner during the copying operation, the working efficiency upon the copying operation decreases extremely.
Incidentally, there is another type of copying machine in which a display indicative of a full state of waste is preliminarily turned on at the time when the condition of the waste container becomes not completely but substantially full of the waste and only a predetermined number of copies are permitted with turning on of the display. This type of copying machine, however, has the same drawback as mentioned above if a number of copies to be produced is larger than the permitted number of copies.